Umm...this is 5 hours after I put the new SC in.
Does the PTO have to come off again? It ran for about 5 mins after it happened, I was right by dock.

Yes, the pto needs to come off to find the pieces and inspect the flywheel for damage. Looks like you are lucky that the gear did not come off and drop the needle bearings. Your missing 4 spring washers 1 L-nut, and the retaining nut with the broken piece from the shaft. Also pull the front oil pump cover and see if any of the smaller pieces made it up there. If you find all the pieces intact and not chewed up you'll be fine, Who built the charger?

I wonder if it's the ebay metal clutch washers? Those look thicker than Riva's

They do look thick.
Wonder what the slip was at on this charger? Dont really see how that would snap the end of the shaft unless the shaft spins in the collar enough to cause an overtightening effect on the nut. The momentum is going the right diirection to make this possible. Seeing the thickness of those washers makes me assume by the looks of it that charger was locked up tight. Unless the OP tells us otherwise what the slip was at. I know Joe's charger was set-up tight around 20lbs. Hmm. Would be nice to see a pic of the oil holes in the shaft collar under the gear. Joe do you have a pic of yours?